...

• F-Stop is divided by 10X with PxrCamera.  RMAN-20475
• Chromatic aberration is different in RIS than XPU with RfM.  RMAN-20474
• When loading 25.0 in RfM, several warnings are in the script editor about being unable to validate OCIO configuration path.  RMAN-20565

• RfM fails to export rib to a folder that has spaces in the name.  RMAN-20517

• Bezier and Constant interpolation types for ramps are not supported.  RMAN-19486
• Overriding PYTHONPATH can cause denoising to fail.  RMAN-20546
• If you are using the RenderMan Hydra Render Delegate in Maya, and are rendering when you close Maya, there will be a crash on exit.  RMAN-18308
• LamaIridescence has no out color visible in Hypershade.  You can manually get the output plug, or you can hit the "hamburger" icon for the node several times to cause the plug to be visible.  RMAN-20584
• Cannot render to "it" in Maya 2020.  RMAN-20183

...

Known Limitations - Existing

...

• Shading
  
  • PxrUnified integrator is currently experimental as it does not yet support all the standard rendering features.
  • <primstr:nameofvalue> substitution of data from a constant primvar or user attribute on an object for dynamic filename substitution is not yet working for the gettextureinfo() OSL call.
  • Using the ' . ' character in the handle for an OSL shader could cause unpredictable results during re-rendering.
• General rendering
  • Load on demand procedurals are not supported anymore, all procedurals are now loaded immediately.
  • We do RenderMan does not read point data from OpenVDB files.
  • Per-Instance baking is not supported, only the reference instance.
  • 3d baking: no direct bake-to-ptex support.
  • PxrBakePointCloud cannot directly render ptex.
  • Sample /+ Display filter plug-ins do not have access to lighting services for light dependent effects, e.g. lens flare.
  • Adding new mesh light on existing geometry during IPR results in double geometry.
  • Motion blurred polygons do not motion blur normals when deformed. Use Subdivision meshes instead.
  • When attempting to access an array primvar, you must first check the size of the array primvar and allocate the appropriate space. Not doing so may lead to a crash.
  • Points and curves cannot be used as geometric lights.
  • Analytical lights placed inside non-aggregate volumes may yield artifacts when made visible to the camera. As a work around, the light camera visibility should be turned off, and a geometry with a similar shape should be used (visible to camera, invisible to transmission and indirect rays), with the proper emissive bxdf.
  • Indirect Path Guiding in the PxrUnified integrator causes a crash.
• Bridge Products:
  • RfH: Soloing MaterialX Lama nodes in complex shading networks can give an incorrect result.

...